still stuck with this, i would hate to have to reinstall the server, runing zendisc with -v10 gives this output:
[zenoss@zenfront ~]$ /opt/zenoss/bin/zendisc run --now -d 10.12.42.97 --monitor zenag --deviceclass /Network/Agencia/Interior/AG 2.0/AG_12_42 -v10
2013-09-05 09:43:16,796 DEBUG zen.ZenDisc: Run in foreground, starting immediately.
2013-09-05 09:43:16,798 DEBUG zen.ZenDisc: Starting PBDaemon initialization
2013-09-05 09:43:16,798 INFO zen.ZenDisc: Connecting to localhost:8789
2013-09-05 09:43:16,799 DEBUG zen.pbclientfactory: Starting connection...
2013-09-05 09:43:16,799 DEBUG zen.ZenDisc: Logging in as admin
2013-09-05 09:43:16,802 DEBUG zen.pbclientfactory: Connected
2013-09-05 09:43:16,802 DEBUG zen.pbclientfactory: Cancelling connect timeout
2013-09-05 09:43:16,802 DEBUG zen.pbclientfactory: Sending credentials
2013-09-05 09:43:16,805 DEBUG zen.pbclientfactory: Cancelling connect timeout
2013-09-05 09:43:16,805 INFO zen.ZenDisc: Connected to ZenHub
2013-09-05 09:43:16,805 DEBUG zen.ZenDisc: Setting up initial services: EventService, DiscoverService
2013-09-05 09:43:16,806 DEBUG zen.ZenDisc: Chaining getInitialServices with d2
2013-09-05 09:43:16,806 DEBUG zen.pbclientfactory: pinging perspective
2013-09-05 09:43:16,808 DEBUG zen.ZenDisc: Loaded service EventService from zenhub
2013-09-05 09:43:16,808 DEBUG zen.ZenDisc: Loaded service DiscoverService from zenhub
2013-09-05 09:43:16,809 DEBUG zen.ZenDisc: Queued event (total of 1) {'rcvtime': 1378384996.808934, 'severity': 0, 'component': 'zendisc', 'agent': 'zendisc', 'summary': 'started', 'manager': 'zenfront', 'device': 'zenag', 'eventClass': '/App/Start', 'monitor': 'zenag'}
2013-09-05 09:43:16,809 DEBUG zen.ZenDisc: Sending 1 events, 0 perf events, 0 heartbeats
2013-09-05 09:43:16,810 DEBUG zen.ZenDisc: Calling connected.
2013-09-05 09:43:16,810 DEBUG zen.ZenDisc: fetching monitor properties
2013-09-05 09:43:16,810 DEBUG zen.pbclientfactory: perspective ponged
2013-09-05 09:43:16,811 DEBUG zen.pbclientfactory: Cancelling ping timeout
2013-09-05 09:43:16,821 DEBUG zen.ZenDisc: Getting threshold classes...
2013-09-05 09:43:16,864 DEBUG zen.ZenDisc: Loading classes ['Products.ZenModel.MinMaxThreshold', 'Products.ZenModel.ValueChangeThreshold']
2013-09-05 09:43:16,865 DEBUG zen.ZenDisc: Fetching default RRDCreateCommand...
2013-09-05 09:43:16,871 DEBUG zen.ZenDisc: Getting collector thresholds...
2013-09-05 09:43:16,883 DEBUG zen.thresholds: Updating threshold ('high event queue', ('zenag collector', ''))
2013-09-05 09:43:16,883 DEBUG zen.thresholds: Updating threshold ('zenmodeler cycle time', ('zenag collector', ''))
2013-09-05 09:43:16,883 DEBUG zen.ZenDisc: Getting collector plugins for each DeviceClass
2013-09-05 09:43:17,041 INFO zen.ZenDisc: Looking for 10.12.42.97
2013-09-05 09:43:17,042 DEBUG zen.ZenDisc: Found IP 10.12.42.97 for device 10.12.42.97
2013-09-05 09:43:17,047 DEBUG zen.ZenDisc: Scanning device with address 10.12.42.97
2013-09-05 09:43:17,047 DEBUG zen.ZenDisc: findRemoteDeviceInfo.inner: Doing SNMP lookup on device 10.12.42.97
2013-09-05 09:43:17,068 DEBUG zen.ZenDisc: findRemoteDeviceInfo.inner: override acquired community strings
2013-09-05 09:43:17,068 DEBUG zen.ZenUtils.snmp: findBestConfig: configs=[]
2013-09-05 09:43:41,291 DEBUG zen.icmpecho: Identifier mismatch: packet=26699, expected=8732 -- ignoring
2013-09-05 09:43:41,335 DEBUG zen.icmpecho: Identifier mismatch: packet=53918, expected=8732 -- ignoring
2013-09-05 09:43:41,388 DEBUG zen.icmpecho: Identifier mismatch: packet=63284, expected=8732 -- ignoring
2013-09-05 09:43:41,436 DEBUG zen.icmpecho: Identifier mismatch: packet=4463, expected=8732 -- ignoring
2013-09-05 09:43:46,806 DEBUG zen.pbclientfactory: pinging perspective
2013-09-05 09:43:46,808 DEBUG zen.pbclientfactory: perspective ponged
2013-09-05 09:43:46,808 DEBUG zen.pbclientfactory: Cancelling ping timeout
2013-09-05 09:44:16,806 DEBUG zen.pbclientfactory: pinging perspective
2013-09-05 09:44:16,808 DEBUG zen.pbclientfactory: perspective ponged
2013-09-05 09:44:16,808 DEBUG zen.pbclientfactory: Cancelling ping timeout